Cyrtocarpa edulis fruit and its immunostimulant effect on Almaco Jack Seriola rivoliana: in vitro, in vivo and ex vivo studies.

The present study investigates for the first time chemical, proximate analyses and immunostimulant effect of Cyrtocarpa edulis fruit (CeF). Three design experiments were carried out to evaluate immunostimulant effect of C. edulis fruit: in vitro, in vivo and ex vivo studies in juveniles Almaco jack Seriola rivoliana. In general, nutraceutical studies performed by gas chromatography/mass spectrometry (GC-MS) in CeF revealed a major quantity of the carbohydrate groups and phytosterols such as ß-sitosterol. Their phytochemical and antioxidant values exposed a significant content of total phenols, flavonoids, and tannins, showing an antioxidant capacity against hydroxyl and superoxide radical. The in vitro results confirm that CeF is edible and enhanced the innate immune response in head-kidney leukocytes after 24 h of immunostimulation. The in vivo results showed that myeloperoxidase, nitric oxide production, as well as antioxidant enzymes were enhanced in skin mucus of those fish fed with CeF. Interestingly in the intestine, IL-ß, TNF-α, MARCO and Piscidin gene expression were up-regulated in fish fed with C. edulis after 4 weeks. Finally, ex vivo experiments showed an important enhancement on cellular parameters (phagocytosis, respiratory burst, myeloperoxidase, and nitric oxide production) in head-kidney leukocytes of fish fed CeF and intraperitoneally infected with A. hydrophila. The results demonstrate that C. edulis fruit (0.5%) represents an available phytochemical and antioxidant rich alternative with great potential as fish immunostimulant additive.

Evaluation of ToxA and Vibrio parahaemolyticus lysate on humoral immune response and immune-related genes in Pacific red snapper.

Immunogenicity of ToxA and Vibrio parahaemolyticus lysate was evaluated in a double immunostimulation scheme in Pacific red snapper after V. parahaemolyticus infection. Three groups of Pacific red snapper were intraperitonealy (i.p.) injected with phosphate-buffered saline (PBS group), ToxA of V. parahaemolyticus (ToxA-Vp group) or V. parahaemolyticus lysate (lysate-Vp group) (first injection, day 1; second injection, day 7). Fish were subsequently infected with live V. parahaemolyticus. Humoral immune parameters in skin mucus and serum were evaluated on days 1, 7, 8 and 14 days post-immunostimulation and 7 days post-infection. Moreover expression of immune-related genes was quantified by real time PCR in head-kidney leukocytes, spleen, liver, and intestine. The ToxA-Vp-treated group showed a higher anti-protease and catalase activity in skin mucus when compared with the PBS group. Measurements of SOD and CAT activities showed an increment in both activities a day after the second boost with ToxA-Vp or lysate-Vp. Interestingly, IgM levels in mucus and transcripts were enhanced followed the ToxA-Vp treatment even after challenge. Furthermore, IL-1ß was strongly expressed in all analyzed cell or tissues followed ToxA-Vp or Vp-lysate treatments. Finally, SOD and CAT gene expression was up-regulated in fish immunostimulated with either treatment ToxA-Vp or lysate-Vp, mainly after infection in head-kidney leukocytes and intestine. This is the first study where the effects of ToxA from V. parahaemolyticus in the immune system of Pacific red snapper was evaluated. These results suggest that ToxA-Vp would positively affect humoral immune response and up-regulate expression of genes involved in the immune system function; and could help in the control of V. parahaemolyticus infection in Pacific red snapper Lutjanus peru, an economic important fish in Mexico.